It is known that fixed metal ladders are used in different scopes, for example for safety and emergency purpose in the event of a fire in buildings; such ladders are entirely made of metal and are mainly installed outside buildings. Other fixed metal ladders find application inside the buildings themselves, to access mezzanine floors or ceilings, and as service access in shops, offices and public places.
Known ladders of this kind typically comprise a bearing structure or frame that supports a plurality of walking surfaces forming the steps; said ones are constrained to the bearing structure by welds and/or bolts.
It has been found that these known ladders show considerable drawbacks, both from the construction point of view and in the assembly or installation step.
As regards the construction aspect, said ladders involve the setup of multiple components, often of considerable size to be assembled to one another for making the bearing structure, whereas the multiple welds required to assemble said structure are difficult, require the work of specialised personnel as well as in-depth checks on the suitable resistance and hold.
Moreover, it should be noted that at said welds it is necessary to carry out protection operations with coatings suitable for preventing the deterioration thereof. Also the transport of the bearing structures to the installation site can be difficult as it requires specific means, considering the size of the components which can reach several metres in length. This also implies considerable overall costs.